#include<iostream>
#include<vector>
using namespace std;
typedef long long ll;
const int N = 100010;
int n;
int q[N], tmp[N];
ll merge_sort(int l, int r){
    if(l >= r) return 0;
    int mid = l + r >> 1;
    ll res = merge_sort(l, mid) + merge_sort(mid + 1, r);
    int k = 0, i = l, j = mid + 1;
    while(i <= mid && j <= r){
        if(q[i] <= q[j]) tmp[k ++] = q[i ++];
        else{
            tmp[k ++] = q[j ++];
            res += mid - i + 1;
        }
    }
    while(i <= mid) tmp[k ++] = q[i ++];
    while(j <= r) tmp[k ++] = q[j ++];
    for(int i = l, j = 0; i <= r; i ++, j ++) q[i] = tmp[j];
    return res;
}
int main(){
    cin >> n;
    for(int i = 0; i < n; i ++) cin >> q[i];
    cout << merge_sort(0, n - 1);
    return 0;
}